Posterior reversible encephalopathy syndrome (PRES) and venous thrombosis are frequently encountered first in the emergency setting and share some common characteristics. The clinical presentation in both entities is vague, and the brain parenchymal findings of PRES syndrome may resemble those of venous thrombosis in some ways. Both entities often occur in a bilateral posterior distribution and may be associated with reversible parenchymal findings if the inciting factor is treated. These diagnoses should be at the forefront of the differential diagnosis when confronted with otherwise unexplained brain edema, among other findings described in this article.